Process of manufacturing reconstituted tobacco of light color

ABSTRACT

A process of treating tobacco in the manufacture of reconstituted tobacco is disclosed wherein the color of the finished reconstituted product is lightened by the removal of basic polyphenols present in the starting batch. The process involves washing the tobacco with water to form an aqueous extract thereof, separating the extract and treating it with absorbent agents such as activated alumina or polyamids to remove the basic polyphenols and finally reincorporating the extract minus the removed polyphenols into the fibrous tobacco mass.

United States Patent [72] Inventors Harry Jacin Norwalk; Joseph V.Fiore, Fairfield, Conn. [21] Appl. No. 639,032 [22] Filed May 17, 1967[45] Patented Feb.9, 1971 [73] Assignee American Machine 8: FoundryCompany a corporation of New Jersey [54] PROCESS OF MANUFACTURINGRECONSTITUTED TOBACCO OF LIGHT COLOR 1 Claim, No Drawings [52] US. Cl131/143, 131/17 [51] Int. Cl A241) 03/14, A24b 15/08 [50] Field ofSearch131/15,17, l40144(1nd. all) [56] References Cited UNITED STATES PATENTS267,764 11/1882 Wood 131/17UX 720,830 2/1903 Marsden 13 l/17UX 3,255,7606/1966 13l/2X 802,487 10/1905 131/143 3,351,066 11/1967 Colgate 131/1403,390,685 7/1968 Von Bethmann et al. 131/143 3,145,717 8/1964 Osborne etal. l31/143X Primary Examiner-Melvin D. Rein Attorneys-George W. Priceand Murray Schaffer ABSTRACT: A process of treating tobacco in themanufacture of reconstituted tobacco is disclosed wherein the color ofthe finished reconstituted product is lightened by the removal of basicpolyphenols present in the starting batch. The process involves washingthe tobacco with water to form an aqueous extract thereof, separatingthe extract and treating it with absorbent agents such as activatedalumina or polyamids to remove the basic polyphenols and finallyreincorporating the extract minus the removed polyphenols into thefibrous tobacco mass.

raocsss or MANUFACTURTNG RECONSTITUTED TOBACCO or [.IGHT COLOR Thepresent invention relates to a method for the preparation ofreconstituted tobacco sheet and more particularly to an improved processfor preparing light colored reconstitutet. tobacco sheet, despite theuse of heat as a processing aid at any step of the process.

The commercial method for the manufacture of reconstituted tobacco sheetrequires the application of heat at some stage in the processing e.g.either in the preparative stages and/or in the drying. it is known thatthe color of the finished tobacco product darkens because of theheating; the level of darkening being a function of temperature andheating time. As a rule, it is desirable to produce a light coloredtobacco sheet and various steps are taken to achieve this goal, forexample, the addition of dyes or coloring chemicals, the addition a ofcolor masking agents (whiteners") such as titanium dioxcially ifexcessive amounts are needed to produce the desired results. Excessiveuse of dyes can produce leaching" problems while excessive use ofwhiteners" can result in sheets which are greyish in appearance or lackproper physical structure. In the case of controlled temperature andheating time, undesirable limits are put upon the manufacturingprocedures. The invention herein revealed makes it possible to produce alight colored, reconstituted tobacco sheet without the resort to dyesfor color preservation and without any undue limitations on thetemperature and heating time used in the process. This is achieved byselectively removing from the tobacco the agents responsible for thedarkening of the tobacco on heating.

In the preparation of additive reconstituted tobacco, tobacco, such asstems, field scrap, cuttings, whole leaf and the like, -is preferablyuniformly comminuted and formed into tobacco sheet suitable for latermachine processing. On the other hand, in the preparation of all-tobaccoreconstituted sheet or i in reconstituted sheets wherein a moreefficient utilization of the natural gums of the tobacco is desired, thetobacco is usually ground to colloid-forming size particles by a wetprocess or refining. However, the large amount of energy and timerequired for the preparation of these colloid-forming size' tobaccoparticles has limited its use for the preparation of reconstitutedsheets.

To reduce the energy expended and time involved to comminute the tobaccoparticles in the wet process, it is desirable to cook the tobacco priorto refining. This cooking operation reduces the refining time andsimultaneously improves the physical properties of the finished product.However, the cooking causes darkening of. the tobacco and hence darkensthe sheets made from this cooked tobacco material, thereby making, suchsheets unacceptable in a number of manufac-' tured tobacco products.

Many attempts have been made heretofore to produce reconstituted tobaccosheets using heat at some stage in the processing without the adversedarkening of the tobacco,

using various techniques and methods, but, in general, such at- Thepresent invention provides a solutionto this longstand problem, andresults in a great reduction in energy and time required to obtain goodquality reconstituted tobacco sheets of acceptable color. A furtherobject of the present invention is to provide a method for producing alight colored reconstituted tobacco sheet despite the use of heat as aprocessing aid.

A still further object of the present invention is to remove Stillanother object of the present invention is to provide a.

method for accomplishing all of the above, which can be used inprocessing large quantities of tobacco resulting in a reconstitutedsheet of tobacco having an acceptable color and to do so in aneconomical and easily controlable method.

Other objects and advantages of the present invention will be apparentfrom the further reading of the specification and of the appendedclaims.

Tobacco as defined for this invention includes any type of tobaccosuitable for the manufacture: of reconstituted tobacco sheet, such asstern, veins, scrap and waste tobacco, cuttings and the like, as well aswhole leaf or portions thereof.

In general, the method of the present invention discloses a method ofremoving from the tobacco washings the agents responsible for thedarkening of the tobacco when it is exposed to heat. The treatedwashings are then returned to the tobacco being processed, and theproduct prepared in a conventional manner to provide a reconstitutedtobacco sheet of good physical properties without detriment to the sheetcolor. lthas long been commonly believed that the agents responsible forthe darkening of the tobacco on cooking were the carbohydrates and theamino acids, which react during the heating to form dark coloredcompounds, the process being called the Mai1lard" reaction. We havediscovered that neither'the carbohydrates nor the :amino acids darkenthe tobacco significantly on heating, but that polyphenols contained inthe tobacco, especially the basic-polyphenols, do cause a significantdarkening of the tobacco upon exposure to heating. This phenomenon isalso pH dependent.

A series of tests were run to isolate and determine the agents whichcaused tobacco darkening upon heating. The following procedureillustrates how the polyphenols were identified as the agents whichcause tobacco darkening during heating. A sample of Bright stern dustweighing 10 g. was mixed with ml. of distilled water. The slurry wasfiltered on a Buchner funnel using Whatrnan No. l filter paper. Thefilter cake and filtrate were retained. The filter cake was subsequentlymixed with 90 ml. of a predleterrnined liquid and the slurry transferredto a vessel, such as a mason jar, which was sealed and placed in apressure cooker, where it washeated at 250 F. at 15 psi. for 2 hours.Upon cooling, three sheets having a thickness of about 0.25-0.30 mm.were cast from the slurry on 20 cm. x 20 cm. glass plates. The sheetswere dried in an ovenat ll0-l15 C. for about 15-20 minutes and the colorof each sheet was read in a Gardner automatic color difference meter,Model AC-2 A, Series 200. Readings were made by placing the plate overthe Gardner aperture with the tobacco side facing the aperture. A numberof readings were 'taken at different points on each plate so as toobtain an overall average.

The test results in table lwere obtained with various add i tives in thepredetermined liquid and serve to illustrate that polyphenols are theagents causing the darkening of the tobacco on exposure to heat.Water-washed Bright stern dust was used in all cases, unless otherwiseindicated. The weight of the washed tobacco in each sample was 7 g. dryweight and this was suspended in 90 ml. of liquid prior to heating.

3 4 TABLE 1.COLOR F SHEETS PREPARED FROM BRiGglITggglgi DUST HEATED INSOLVENIS CONTAINING VARIOUS pH before pH after Materials heating heatingRd a+ b+ Washed tobacco plus water (positive control) 24 9 3. 1 21.5Unwashed tobacco plus water 16. 3 Washed tobacco plus washings (negativecontrol) 16. 4 Washed tobacco plus sucrose (2 gm.) plus water 25. 4Washed tobacco plus glucose (2 gm.) plus water.. 25. 2 Washed tobaccoplus fructose (2 gm.) plus water 24. 7 Washed tobacco plus sucrose,fructose, glucose (2 gm. each) plus water 26. 8 Washed tobacco plustryptone (1 gm.) (casein digest) plus water 22. 3 2. 7 Washed tobaccoplus tryptone plus sucrose (1 gm. each) plus water. 22. 9 2. 5 Washedtobacco plus tryptone plus glucose (1 gm. each) plus water 22. 2 3. 3Washed tobacco plus tryptone plus fructose (1 gm. each) plus water 22. 02. 5 Washed tobacco plus tryptone plus glucose, fructose, sucrose (1 gm.each) plus water. 21. 9 3. 8 Washed tobacco plus water plus acidicpolyphenols 22. 6 3. 5 Basic polyphenols plus washed tobacco plus water12. 4 5. 8 Acidified basic polyphenols plus washed tobacco plus wate 17.2 4. 7 Washed tobacco plus Pb acetate sol. (10%) water 23. 4

NorE.Rd=Brightness factor; black=0; white=l00; a+, b+=Coordinates on achromaticity diagram; P Acetate=lead acetate.

The polyphenol fractions shown in table I were obtained as follows: 90ml. of a tobacco-water extract, prepared as described above, was mixedwith ml. ofa 10 percent lead acetate solution, and the formedprecipitate was removed by centrifugation. This precipitate comprisedthe acidic polyphenol fraction.

Adding more lead acetate solution to the supernatant caused no moreprecipitation. An alkaline reagent, such as ammonium hydroxide (NH4OH)was added to the supernatant until the pH was about 8.59. The formedprecipitate, which was collected by centrifugation, constituted thebasic polyphenol fraction.

As seen from the experimental results shown in table I, the basicpolyphenols make a sheet darker than even the negative control (Rdreadings 12.4 and 16.4, respectively). Furthermore, it is seen thatwhile acidifying the basic polyphenols improves the color, it is stillfar below the positive control (Rd readings of 17.2 and 24.9,respectively). These results show that the sugars and amino acids do notaffect the sheet color and similarly neither does the lead acetatesolution used to precipitate the polyphenols.

Processes for the neutralization or removal of the polyphenol fromtobacco with the addition of chemical substances are fully disclosed anddescribed in our copending application, Ser. No. 639,066 filed even dateherewith. The present disclosure confines itself to the removal ofpolyphenols without chemical substances.

in order to extract the basic polyphenols from the tobacco withoutadding any chemical additive to the reconstituted tobacco sheet, thetobacco water washings can be treated with adsorbent material, whichadds nothing to the extract, but selectively removes the darkening agentor agents by adsorption. For example, tobacco water washings are passedthrough a column containing a selected adsorbent material, such asactivated alumina. The adsorbent removes the darkening material, butleaves the other valuable tobacco constituents unchanged in the extract.The treated extract is then recombined with the original washed tobaccoand the combination is processed into reconstituted tobacco sheet, whichretains its commercially acceptable light color with no additives.

In accordance with the present invention, untreated tobacco, such asbroken leaves, cuttings, stemmings, various fragments or waste, fieldscrap, is subjected to a water extraction operation so as to separatethe water-soluble constituents.

The water-soluble constituents of the tobacco or extract are separatedfrom the insoluble portion by any convenient process, such as draining,pressing, or centrifuging. The aqueous extract contains variouswater-soluble materials, including polyphenols. This aqueous extract canthen be passed through a column containing an adsorbent material, suchas activated alumina. Continuous operation in a column can be effectedby placing the adsorbent material and passing the aqueous extractcontinuously through a column. The adsorbent material removes thecolor-forming bodies, but leaves the other valuable tobacco constituentsunchanged in the column effluent. The effluent is then recombined withthe original washed tobacco and the combination is processed in aconventional form and a light colored reconstituted tobacco sheet isproduced. The extracted coloring materials can be eluted from theadsorbent so that it can be reused as desired.

The following examples are set forth to demonstrate the method of thisinvention.

A glass column (25 cm. x 3 cm.) was filled with a slurry of 100 gm. ofactivated alumina (8l4 mesh) in water. The water was allowed to drainand the column was washed repeatedly with about 500l000 ml. fresh water.A water extract of tobacco dust obtained by the method describedpreviously was passed over the column at a flow rate such that effluentwas collected at 0.5 ml. per minute. The column was then washed withwater until the washings were colorless. The combined water washings andcollected effluent were then concentrated to 100 ml. under vacuum in aflash evaporator using a temperature range of 36-38 C. The solidscontent in the concentrate, as well as in the original water tobaccoextract were determincd and the recovery of material from the columncalculated from these values. The test results are presented in table 2.

TABLE 2.SOLIDS IN TOBACCO-WATER EXTRACTS AND IN COLUMN EFFLUENT FROMALUMINA COLUMNS Solids Solids in Solids put recovered in 0 1120 onconcentrated Tobacco extract, column efliuents Percent Sample stemspercent (gm.) (gm.) recovery 1 Bright-.. 4.50 9.00 6.73 74.5 2 d 4. 579. 14 6. 72 74. 5 3 .-do. 4. 52 9. 04 6. 52 72. 5 5 5 4 4. 55 9. 10 3.17 6. 34 3. 15 6. 30 5. 63 89. 2 3. 15 6. 30 5. 64 89. 3 3. 14 6.28 5.67 90. 5

The figures in table 2 show that the solids recovery is 73- 75 percentfor Bright stem extracts and 89-91 percent for Penn. stem extracts.

The material not removed from the column by water washing was eluted offby passing 2 normal formic acid through the column. Fractions werecollected at a rate of 0.5 ml. per minute. The eluted samples were verydark in color. The 2 normal formic acid removed all the adsorbedmaterial leaving the activated alumina free of color. The alumina waswashed with water until free of acid, dried in the oven l30-l40 C.)overnight and used again.

The formic acid was removed from the eluate (i.e., the

basic-polyphenols) by evaporation under vacuum in a flash evaporator.The remaining dark brown material was made up to a ml. volume with waterand tested for carbohydrates by a thin layer chromatographv method. suchas rlpcorihri in the Journal of Chromatography l8, l70-l74 (1965 Samplesof the effluent concentrate from the column previously referred to aswell as the original tobacco-water extract were also examined forcarbohydrates. The results showed that practically all of thecarbohydrates found in the original tobacco-water extract were recoveredin the concentrated effluent while only significant amounts were foundin the formic acid eluate.

It should be noted that the material. which could not be removed fromthe column by water could be eluted off by other suitable solvents, suchas 50 percent ethanol containing 2 normal HCl or by 2 normal HClsolution. Advantageously, formic acid is preferred, since it is easilyremoved by evaporation under vacuum. This makes it possible to recoverthe solids from the formic acid eluate and their subsequent utilizationin the color experiments. In an operation where these solids are of noconsequence, their removal from the alumina would be carried out moreeconomically with a 2 normal HCI solution.

The effluent concentrates were made up to volume and recombined with thewashed tobacco. The slurries were treated in a manner as describedabove. The obtained sheets were examined in a Gardner colorimeter, andthe results are presented in table 3.

these materials are fine meshed and pack easily in the columns, so as toreduce flow through the columns. A pressure source would be necessary toobtain satisfactory flow through columns using these adsorbentmaterials. It is understood that the preferred adsorbents need not beused in a column. They can also be employed effectively in slurry-typeremoval polyphenols.

By the practice of the present invention, there is produced areconstituted tobacco sheet using heat, which contains all the desirableportions of the original tobacco, and which is lighter in color thansheets made of untreated tobacco.

Various changes and modifications may be made in practicing thisinvention without departing from the spirit and scope thereof, andtherefore, the invention is not to be limited, except as defined in theappended claims.

We claim:

TABLE fir-GARDNER READINGS 0N SHEETS PREPARED WITH VARIOUS EFFLUENTS ANDELUATES FROM ALUMINA COLUMNS pH of Tobacco Fraction tob. slurry Rd a+ b+Brlght Efliuent con- 5.8 21.5 3 7 17.5

centrate. Do -do 5.6 24.6 Do do 4.7 24.6 5.4 34.4 Do 3. 2 17. 4 4. 1 22.7 Bright (positive c 1) 5. 3 24. 8 3. 9 35. 0 Bright (negative control)4. 8 16. 8 4. 8 22. 3 Penn 6.3 19.6 so 24.6

3. 8 17. 1 6. 1 23.3 7.0 19.3 5.2 24.6 6. 2 17.4 5. 3 22. 8 Efliuentcon- 5.1 15.8

centrate. Bulgarian (postive control) 6.7 15.3 Bulgarian (negativecontrol) 5.2 11. 3

Note.--Posltive control consists of washed tobacco (7 gm. Negativecontrol consists of washed tobacco plus the obtained washing The figuresin table 3 show that the effluent concentrate from the adsorbent columnis similar in its color properties to the positive control, while theformic acid eluate, after removing the formic acid and adjusting tovolume with water, is similar to the negative control. This isparticularly apparent in the Rd values.

Adsorbents, other than activated alumina, were examined. Regeneratedalumina worked as well as unused alumina.

Polyamide and silica gelalso gave satisfactory results.

Other adsorbent materials could be used, such as magnesol, silicic acidor adsorption alumina, and the like. However,

ry weight) plus new water.

